Ubiquitin-Fluorescein-labeled (FLR-Ub)

Post-translational modification of proteins by ubiquitin (Ub) is a key regulatory process that impacts almost all cellular functions. Apart from the established role of Ub in protein degradation, it is implicated in cell signaling, DNA damage response, protein trafficking, cell-cycle progression, inflammation, immune response and regulation of apoptosis. Ubiquitylation occurs through isopeptide linkage between the C-terminus of Ub and the e-amino group of a lysine (Lys) residue on the target substrate. Ub itself has seven Lys residues (6, 11, 27, 29, 33, 48, and 63), any of which can participate in further ubiquitylation, generating polyUb chains. Monitoring the ubiquitylation of target proteins or the growth of polyubiquitin chains has traditionally been carried out with either radiolabeled or epitope-tagged ubiquitin requiring long and laborious detection methods. Fluorescently labeled ubiquitin provides a rapid, facile technique for studying ubiquitin conjugation in vitro. Unlike others, BioVision’s fluorescein-labeled ubiquitin carries a single fluorescein molecule attached at a defined location and avoids modification of either the N-terminus or Lys side chains.